Evidence for singular-phonon-induced nematic superconductivity in a topological superconductor candidate Sr<sub>0.1</sub>Bi<sub>2</sub>Se<sub>3</sub>.
basic_science · Level V
Where this comes from
- Record sourced from PubMed, PMID 31243284.
- Also identified by DOI 10.1038/s41467-019-10942-2 and PMC identifier 6594966.
- Licence recorded as CC BY.
- The licence permits redistribution, so the abstract is shown in full and the full text is available from the publisher.
Abstract
Superconductivity mediated by phonons is typically conventional, exhibiting a momentum-independent s-wave pairing function, due to the isotropic interactions between electrons and phonons along different crystalline directions. Here, by performing inelastic neutron scattering measurements on a superconducting single crystal of Sr<sub>0.1</sub>Bi<sub>2</sub>Se<sub>3</sub>, a prime candidate for realizing topological superconductivity by doping the topological insulator Bi<sub>2</sub>Se<sub>3</sub>, we find that there exist highly anisotropic phonons, with the linewidths of the acoustic phonons increasing substantially at long wavelengths, but only for those along the [001] direction. This observation indicates a large and singular electron-phonon coupling at small momenta, which we propose to give rise to the exotic p-wave nematic superconducting pairing in the M<sub>x</sub>Bi<sub>2</sub>Se<sub>3</sub> (M = Cu, Sr, Nb) superconductor family. Therefore, we show these superconductors to be example systems where electron-phonon interaction can induce more exotic superconducting pairing than the s-wave, consistent with the topological superconductivity.